Rolling mills

ABSTRACT

A FOUR HIGH ROD OR BAR ROLLING MILL, WHEREIN THE WORK ROLLS AND THEIR DRIVE SHAFTS ARE CARRIED FOR ROTATION IN ARMS MOUNTED IN THE MILL FRAME FOR PIVOTAL MOVEMENT ABOUT DEFINED PIVOT AXES (OR A COMMON PIVOT AXIS) EXTENDING PARALLEL TO AND SPACED A FIXED DISTANCE FROM THE STOCK PASS LINE, WHEREBY TO PERMIT ADJUSTMENT OF THE WORK GAP   BETWEEN THE WORK ROLLS. THE SUPPORT ROLLS MAY OR MAY NOT BE CARRIED IN THE ARMS WITH THEIR WORK ROLLS AND ARE MOVABLY MOUNTED SO THAT THEY CAN ALIGN THEMSELVES ON THEIR WORK ROLLS.

Oct. 19, 1971 N. A. TOWNSEND ETAL 3,613,428

ROLLING MILLS Filed Nov. 14, 1968 6 Sheets-Sheet 1 Oct. 19, 1971 N. A. TOWNSEND -T 3,513,423

, ROLLING MILLS 6 Sheets-Sheet I Filed Nov. 14, 1968 Oct. 19, 1971 N. A. TOWNSEND EI'AL ROLLING MILLS 6 Sheets-Sheet 3 Filed Nov. 14, 1968 N. A. TOWNSEND ETA!- 3,513,423

ROLLING MILLS Filed Nov. 14, 1968 s Sheets-Sheet 4.

Oct. 19, 1971 N. A. TOWNSEND ETAL 3,613,428

ROLLING MILLS 6 Sheets-Sheet i 45 F IG 5 Filed NOV. 14, 1958 f \k; 4 4 2} W0 f e 3 5 8 2 O 3\\ 2 |H I L IL FiG.6.

Oct. 19., 1971 N. A. TOWNSEND ET 3,513,428

1101mm MILLS Filed Nov. 14. 1968 6 Sheets-Sheet 6 FIG.7.

United States Patent Ofice Patented Oct. 19, 1971 3,613,428 ROLLING MILLS Nicholas A. Towsend, Bexley Heath, Kent, and Roy R. Oxlade, London, England, assignors to The British Iron and Steel Research Association Filed Nov. 14, 1968, Ser. No. 775,668 Claims priority, application Great Britain, Nov. 15, 1967, 52,090/ 67 Int. Cl. B2111 31/00 U.S. Cl. 72237 20 Claims ABSTRACT OF THE DISCLOSURE A four high rod or bar rolling mill, wherein the work rolls and their drive shafts are carried for rotation in arms mounted in the mill frame for pivotal movement about defined pivot axes (or a common pivot axis) extending parallel to and spaced a fixed distance from the stock pass line, whereby to permit adjustment of the work gap between the work rolls. The support rolls may or may not be carried in the arms with their work rolls and are movably mounted so that they can align themselves on their work rolls.

This invention relates to rolling mills and particularly, but not exclusively, to the design of rod or bar stock rolling mills.

In bar or rod stock rolling in, for instance, a steel mill, the width of the bar leaving the final roll stand depends to a certain extent on the height of the bar leaving the penultimate roll stand. Therefore if the height and width of the stock leaving the final roll stand are both to be maintained within close limits of a desired value, it is desirable to control the roll gap height of both of the final and penultimate roll stands.

In order to achieve this it is necessary to gauge the relevant dimensions of the stock being rolled both between the penultimate and fianl passes and after the final pass, and then by means of a servo mechanism or similar system adjust the respective roll gaps to correct any deviations from the desired height and width.

If such adjustment is to be effective, particularly at the high rolling speeds associated with small cross-section stock, it is important that the inertia of the rolls in their mounting on the rolling mill is low in order that the frequency response of the roll gap adjustment servo system may be adequate to permit the elimination of or at least reduction of errors in the rod or bar stock produced.

It is therefore an object of the present invention to provide a design for a rolling mill stand, particularly but not exclusively for final and penultimate roll passes, in which the work rolls of the stand are adjustably mounted on the frame of the mill so that the roll gap may be adjusted, and in which the inertia to be overcome in adjusting the roll gap is low in consideration of the masses of the machine elements associated with providing sufiicient structural strength and rigidity to withstand rolling loads.

Accordingly the present invention provides a rolling mill stand comprising a frame and two work rolls drivably carried on said frame in which at least one of said work rolls is carried for rotation in an arm which is pivotally mounted on said frame, whereby to permit adjustment of the work gap between said rolls.

The work rolls are preferably backed up by support rolls, one said support roll being rotatably carried with its associated work roll in said arm.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a general elevation of a close-coupled twin stand four-high bar or rod rolling mill according to the invention taken along the stock pass line,

FIG. 2 is a plan view of the mill,

FIG. 3 is a part cross-sectional view on line AA of FIG. 2,

FIG. 4 is a part cross-sectional view on line B-B of FIG. 2,

FIG. 5 is a view on line DD of FIG. 3,

FIG. 6 is a view on line E-E of FIG. 3, and

FIG. 7 is a partial vertical section of a modification of the support roll mounting.

Referring firstly to FIGS. 1 and 2, it can be seen that the embodiment provides two close-coupled roll stands indicated generally at 10 and 11 each driven in conventional manner from a respective electric motor with reduction gearing indicated generally at 12 and 13.

The two roll stands 10 and 11 of this embodiment are arranged respectively as the final and penultimate roll passes in the rolling of a rod or bar stock indicated at 14. The two stands 10 and 11 are arranged on a common frame 15 in what is known as the No Twist mode of operation in that it is not necessary to rotate the stock being rolled, about its axis, between the two passes. This is of course achieved by the disposition of the two stands at an angle of 90 to one another so that their lines of action are also at 90 to one another.

The two roll stands 10 and 11 each comprise a pair of work rolls 20 and 21 backed up by support rolls 22 and 23 respectively. The work roll 20 and its associated support roll 22 on each of the stands 10 and 11, are each carried for rotation in an arm 24, and the Work roll 21 and its associated support roll 23 of each of the stands 10 and 11, are each carried for rotation in an arm 25. A preferred method of mounting the work rolls 20 and 21 for rotation on their respective shafts in the arms 24 and 25 is disclosed in our co-pending patent application of even date herewith entitled Mill Roll Mountings.

In order that the roll gap between the work roll 20 and 21 may be adjusted, the arms 24 and 25 are each pivotally mounted as cantilevers about an axis indicated at 26 in the frame 15 which is common to the two stands 10 and 11. An opening indicated generally at 28 of rectangular cross-section is provided in the frame 15 in that part of the frame which forms each of the stands 10 and 11; and the arms 24 and 25 of each stand are arranged as a close sliding fit laterally in the respective openings 28 so that they are closely axially located relative to the pivot axis 26 but may pivot freely within the opening 28 about the axis 26. The close sliding fit is best seen in FIGS. 5 and 6.

The upper arm 24 is provided with a generally downwardly directed fork-like structure 40, and the lower arm is provided with a generally upwardly directed fork-like structure 41 closely laterally straddling structure 40. Each of the two arms of each structure 40 and 41 have registering lateral bores 42 and 43 respectively. Bores 42 and 43 register with bores 44 through opposed side walls 45 and 46 of the mill frame. Massive pivot pins 47 extend through bores 44, 43 and 42 from each side wall 45 and 46. The pins 47 are located laterally by heads 48 received in recesses 49 in the side walls 45 and 46. Arms 24 and 25 are thus both pivotally mounted on pins 47.

Arm 24 is also supported on frame 15 by means of a load cell 50 positioned with a line of action passing nearer the mill rolls 20 and 21 than the pivot axis 26.

In order to provide the actual rolling force between the work rolls 20 and 21, the arm 24 which is the upper in each of the stands 10 and 11 is urged downwards by a hydraulic piston and cylinder device such as that shown at 51, or like device such as a screw jack, which has a line of action closely corresponding to that of the load cell 50. Both the load cell 50 and the hydraulic piston and cylinder device 51 are provided with spherical seatings on their respective arms 25 and 24 to allow for the slight angular misalignments which much occur in the action between them.

A separating hydraulic piston and cylinder device 52 is provided acting effectively between the arms 24 and 25 (or preferably between work roll shaft bearing blocks 53) and arranged to act so as to pivot the arms 24 and 25 away from one another against the action of the hydraulic piston and cylinder device 51.

The arrangement is such therefore that the lower arm 25 is supported by the load cell 50; and the upper arm 24 urged away from the lower arm 25 by the separating hydraulic device 52 but urged downwards towards the arm 25 by the loading hydraulic device 51. The hydraulic separating device 52 is supplied with hydraulic fluid under pressure which pressure may be chosen so that all slack between the various elements, that is to say the two arms 24 and 25, the load cell 50, the hydraulic loading device 51 and the hydraulic separating device 52, together with any resilience in the frame 15 is taken up. All surfaces with load path are thus prestressed. The hydraulic loading device 51 is supplied with hydraulic fluid under pressure, which pressure is chosen to force the upper arm 24 down against the action of the separating device 52, and against the action of separating loads imparted to the rolls 20 and 21 by the stock when actual rolling is in progress, to maintain the desired roll gap.

Thus it can be seen that there is provided an arrangement whereby the gap between the rolls 20 and 21 may be controlled by operation of the hydraulic loading device 51 and whereby the actual rolling load applied may be measured by the load cell 50. Thus when the dimension produced on the stock 14 either by the stand or the stand 11 is measured by means of a suitable gauging device (not shown) the roll gap for the respective roll stand 10 or 11 may be adjusted hydraulically by the loading device 51 so that any errors produced by that stand in the desired stock dimension may be continually corrected for the subsequent part of the stock to be rolled.

It is an important feature of this arrangement of the mounting of the rolls 20 and 21 for adjustment of the roll gap, that the arms 24 and 25 are pivotally mounted in the frame 15, as opposed to being slidably mounted in a linear fashion as in conventional rolling mills, thus presenting a considerably lower inertia (for example only five-eighths as much) to the hydraulic loading device 51 for a given total mass of the arms 24 and 25. This results in a higher frequency response for a given capacity of the loading device 51, enabling not only the more rapid correction of errors produced in the rolling operation by that stand but also in a closer control over the errors produced.

It is a further feature of this embodiment of the invention that by removing the pins 47, each arm 24 or 25 may readily be removed from the frame 15 through the opening 28. This enables the whole roll assembly on each arm 24 or 25 to be removed for maintenance if desired. Further the general consideration of the embodiment as shown in FIGS. 1 and 2 makes for a neat and unobstructed working floor level (as indicated in outline only at 30) for the rolling mill. Furthermore the work roll and shaft assembly may be readily withdrawn for maintenance.

The manner in which the shafts on which the rolls and 21 are carried for rotation within the arms 24 and 25 in this embodiment allows for limited pivotal movement of those shafts, in a plane including the line of the stock 14, against a load cell 80 (FIG. 5) whereby the tension produced in the stock 14 by that particular roll stand may be assessed. This manner of mounting the work roll shaft is disclosed in more detail in our copending patent application or even date herewith entitled Stock Tension Control in Rolling Mills.

It will be appreciated that if it is not required to directly measure the rolling load applied between the two rolls 4 20 and 21, the lower arm 25 need not be pivotally mounted in the frame 15, but may rest firmly on an adjustable stop in place of cell 50 with only the upper arm 24 being pivotally mounted for roll gap adjustment.

The separating device 52 may also be used to separate the work rolls when no stock is between them to facilitate their removal for replacement.

An advantage of this embodiment is that only a single roll gap actuator is required in each stand, thereby dispensing with the need for a system for synchronising the action of twin actuators that would normally be needed in a conventional design of mill.

Referring now to FIG. 4 each support roll 22 and 23 is rotatably mounted on its frame arm 24 and 25 by means of a stub axle 60. This form of mounting serves to lower the inertia of the support rolls. Each stub axle 60 carries a part-spherical bearing surface 61 mating with a bearing surface 62 formed on the inner face of the inner race 63 of a roller bearing assembly 64 whose outer race 65 is secured within the roll 22. Bearing surface 61 is formed with a spline 66 movable within a mating groove 67 in bearing surface 62. It will be seen that cooperating surfaces 61 and 62 provide for self-alignment of the support rolls on their associated work rolls.

This self-aligning arrangement would normally only be used in a mill for handling carbon steel bars. For the higher loads associated with rolling alloy steels the support rolls 22 and 23 need not be self-aligning, cambered support and work rolls being used instead.

Referring to FIG. 7 there is shown a modification wherein work rolls 20, 21 are mounted on pivoted frame arms 24, 25 as before, but each support roll is rotatably mounted on the mill frame 15. As shown the roll itself is formed with integral massive stub axles 70 each rotatably borne by tapered roller bearings 71 and 72. In place of the single self-aligning actuator 51 for roll gap modulation, twin screw-jack actuators 73, 74 are provided acting on the outer races of bearings 71 and 72. The inertia of this arrangement is higher than the first embodiment but still significantly less than conventional systems. This arrangement also provides a stiffer mill capable of taking greater rolling loads.

An alternative method for modulating the work roll gap is as follows. The support roll axes are each offset in the same direction away from the plane including the work roll axes. Therefore if the work rolls are allowed to move as a pair towards and away from the plane including the support roll axes, the work rolls will ride down and up respectively the support rolls thus modulating the roll gap.

Further features and advantages of the described mill will be found in our two co-pending applications re ferred to hereinbefore. One particular advantage is that a constant stock pass line is achieved due to adjustability of the angular position of arms 24, 25 about axis 26. This facilitates the setting up of twin or multistand mills and avoids the need in conventional mills for accurate adjustment of stock guides adjacent each stand.

We claim:

1. A rolling mill stand including a frame having an arm and two work rolls, said work rolls being drivably carried in said frame, and said work rolls being backed up by support rolls, said work rolls being carried for rotation in said arm which is pivotally mounted in said frame whereby to permit adjustment of the work gap between said work rolls, at least one of said support rolls being rotatably carried with its associated work roll in said arm.

2. A rolling mill stand including a frame having at least one arm and two work rolls, said work rolls being drivably carried in said frame and said work rolls being backed up by support rolls, said Work rolls and said support rolls having substantially cylindrical outer surfaces for mutual engagement, one of said work rolls being carried for rotation in said arm, means pivotally mounting said arm in said frame, said means defining a pivot axis extending substantially parallel to and spaced apart from the stock pass line between said work rolls, said pivot axis being substantially fixed in position relative to said arm, whereby said arm carrying its associated work roll is pivotally movable about said fixed pivot axis to permit adjustment of the work gap between, said work rolls, and wherein respective bearing means are provided rotatably mounting said support rolls in said frame so that the axes of rotation of the support rolls are movable with respect to the frame for alignment of the support rolls on their associated work rolls.

3. A rolling mill stand according to claim 2 wherein said support rolls are rotatably mounted directly on said frame.

4. A rolling mill stand according to claim 2 wherein said pivot axis of said arm intersects the axis of rotation of the associated work roll carried by said arm.

5. A rolling mill stand according to claim 2 including a work roll drive shaft associated with each said Work roll, each said drive shaft having a free end and a driven end, said work rolls being secured to the free end of the respective drive shafts for rotation therewith, at least one said drive shaft and associated work roll being carried for rotation in said pivotally mounted arm.

6. A rolling mill stand including a frame having two arms and two work rolls, said work rolls being drivably carried in said frame, and said work rolls being backed up by support rolls, said work rolls and said support rolls having substantially cylindrical outer surfaces for mutual engagement, said work rolls being carried for rotation in respective ones of said arms, at least one of which arms is mounted for pivotal movement about an axis substantially parallel to and spaced apart from the stock pass line whereby to permit adjustment of the work gap between said work rolls, said support rolls being rotatably mounted in said frame whereby their axes of rotation are movable with respect to the frame for alignment of the support rolls on their associated work rolls, and a separating device acting effectively between said arms to tend to force said arms apart, whereby said work rolls are urged into preloaded engagement with their associated support rolls.

7. A rolling mill stand according to claim 6 including a Work roll drive shaft associated with each said work roll, each said shaft having a free end and a driven end, said work rolls being secured to the free end of the respective drive shaft for rotation therewith, each said drive shaft and its associated work roll being carried for rotation in a respective one of said arms, wherein each shaft is provided with a bearing block, and wherein said separating device is disposed to act between said bearing blocks.

8. A rolling mill stand according to claim 6 including rolling load applying means acting solely between said support rolls, whereby the rolling load is applied from the support rolls through their associated work rolls to the stock to be rolled.

9. A rolling mill stand including a frame having at least one arm and two work rolls, said work rolls being drivably carried in said frame and said work rolls being backed up by support rolls, said work rolls and said support rolls having substantially cylindrical outer surfaces for mutual engagement, one of said work rolls being carried for rotation in said arm, said frame including a first and a second portion disposed closely adjacent opposite side faces of said arm over a length of said arm, each said portion defining a bore therein aligned on a substantially common axis with the other said bore, said bore axis extending substantially parallel to and spaced apart from the stock pass line between said work rolls, and pivot pin means working in each said bore, said pivot pin means pivotally mounting said arm between said portions for pivotal movement of said arm in said frame about a defined axis to permit adjustment of the work gap between said work rolls, and wherein said support rolls are rotatably mounted in said frame so that their axes of rotation are movable with respect to the frame for alignment of the support rolls on their associated work rolls.

10. A rolling mill stand including a frame having at least one arm and two work rolls, said work rolls being drivably carried in said frame and said work rolls being backed up by support rolls, one of said work rolls being carried for rotation in said arm, means pivotally mounting said arm in said frame, said means defining a pivot axis extending substantially parallel to and spaced apart from the stock pass line between said work rolls, said pivot axis being substantially fixed in position relative to said arm, whereby said arm carrying its associated work roll is pivotally movable about said fixed pivot axis to permit adjustment of the work gap between said work rolls, and wherein respective bearing means are provided rotatably mounting said support rolls in said frame so that the axes of rotation of the support rolls are movable with respect to the frame for alignment of the support rolls on their associated work rolls, one of said support rolls being rotatably carried with its associated work roll in said one arm, a stub axle being formed on said arm rotatably to mount said support roll in said arm, and wherein means is provided for adjusting the work roll gap, said adjusting means comprising an adjustable actuator acting on said stub axle.

11. A rolling mill stand including a frame having at least one arm and two work rolls, said work rolls being drivably carried in said frame and said work rolls being backed up by support rolls, one of said work rolls being carried for rotation in said arm, said frame including a first and a second portion disposed closely adjacent opposite side faces of said arm over a length of said arm, each said portion defining a bore therein aligned on a substantially common axis with the other said bore, said bore axis extending substantially parallel to and spaced apart from the stock pass line between said work rolls, and pivot pin means working in each said bore, said pivot pin means pivotally mounting said arm between said portions for pivotal movement of said arm in said frame about a defined axis to permit adjustment of the work gap between said work rolls, and wherein said support rolls are rotatably mounted in said frame so that their axes of rotation are movable with respect to the frame for alignment of the support rolls on their associated work rolls, one of said support rolls being rotatably carried with its associated work roll in said arm.

12. A rolling mill stand including a frame having two arms and two work rolls, said work rolls being drivably carried in said frame, and said Work rolls being backed up by support rolls, said work rolls being carried for retation in respective ones of said arms, said frame including a first and a second portion disposed closely adjacent opposite side faces of said arms over a length of said arms, each said portion defining a bore therein aligned on a substantially common axis with the other said bore, said bore axis extending substantially parallel to and spaced apart from the stock pass line between said work rolls, and pivot pin means Working in each said bore, said pivot pin means pivotally mounting said arms between said portions for pivotal movement of said arms in said frame about a defined axis to permit adjustment of the work gap between said work rolls, and wherein said sup port rolls are rotatably mounted in said frame so that their axes of rotation are movable with respect to the frame for alignment of the support rolls on their associated work rolls.

13. A rolling mill stand according to claim 1 wherein each said work roll with its associated support roll are carried in an individual arm pivotally mounted on said frame.

14. A rolling mill stand according to claim 13 wherein said two arms are mounted for pivotal movement about a common pivot axis.

15. A rolling mill stand according to claim 1 wherein said support roll is mounted for rotation about a stub axle formed on said arm.

16. A rolling mill stand according to claim 15 wherein said support roll is mounted on said stub axle by means of a self-aligning bearing.

17. A rolling mill stand according to claim 15 including means for adjusting the work roll gap, said means comprising an adjustable actuator acting on said stub axle.

18. A rolling mill stand according to claim 17 including a load sensing device disposed between one said stub axle and the frame to provide a signal indicative of the rolling load.

19. A rolling mill stand according to claim 2 further comprising a second arm that is pivotally mounted in said References Cited UNITED STATES PATENTS 1,900,032 3/1933 Worthington 72--243 3,208,678 9/1965 Pick et a1. 24l232 3,468,151 9/1969 Diolot 72245 3,491,571 1/1970 OBrien 72-244 CHARLES W. LANHAM, Primary Examiner B. J. MUSTAIKIS, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. $613,428 Dated Octo er 19. 971

Inventor(s) N. A. TOWNSEND et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE CLAIMS:

Column 4, Claim 1, Line 63,

after "rolls, insert --one of--.

Signed and sealed this 16th day of July 1974.

(SEAL) Attest:

MCCOY M. GIBSON, JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents 

